Resin for toner binder and toner composition

ABSTRACT

The present invention provides a toner binder for developing electrostatic charge images,  
     which binder comprises a polycondensate polyester resin,  
     said polyester resin being a product formed in the presence of at least one titanium-containing catalyst (A) selected from the group consisting of a titanium halides (A1), a titanium diketone enolate (A2), a titanium carboxylate (A3), a titanyl carboxylate (A4), and a titanyl carboxylate salt (A5).  
     Furthermore, the present invention provides a toner binder for developing electrostatic charge images,  
     which binder comprises a polycondensate polyester resin,  
     said polyester resin being a product formed in the presence of at least one tin-containing catalyst (B) selected from the group consisting of dioctyltin oxide (B1), monobutyltin oxide (B2), and dibutyltin oxide (B3), with the content of tributyltin compounds in (B3) being not more than 250 ppm.

TECHNICAL FIELD

[0001] The present invention relates to a toner binder for dry toners tobe used in electrophotography, electrostatic recording, electrostaticprinting and so on.

BACKGROUND ART

[0002] When polyester-based toner binders for dry toners are used intoners, it is easy to provide the toners with both the ability to befixed even at a low heated roll temperature (low temperature fixability)and the inability to fuse to the heated roll even at a high heated rolltemperature (hot offset resistance) simultaneously, in particular goodlow temperature fixability, and therefore their consumption is showing atendency toward increase.

[0003] Lately, electrophotography, electrostatic recording,electrostatic printing and the like techniques have come into wide use.They are now carried out under more diversified environmental conditionsthan before and, thus, when conventional toners are used in lowtemperature and low humidity environments for a long period of time, thequality of images on the photoconductor tends to deteriorate in certaininstances. With the prior art toner binders (e.g. Japanese KokaiPublication 2002-148867), it is difficult to prevent the image qualityfrom deteriorating while maintaining various toner characteristics.

SUMMARY OF THE INVENTION

[0004] The present inventors made intensive investigations in an attemptto develop a polyester-based toner binder capable of maintaining goodlow temperature fixability and hot offset resistance and preventingimage quality deterioration even under low-temperature and low-humidityconditions and, as a result, found that such a toner binder can beobtained by using a polyester resin formed in the presence of a specificcatalyst. Based on such and other findings, now the present inventionhas been completed.

[0005] Thus, the present invention consists in a toner binder fordeveloping electrostatic charge images, which binder comprises apolycondensate polyester resin,

[0006] said polyester resin being a product formed in the presence of atleast one titanium-containing catalyst (A) selected from the groupconsisting of titanium halides (A1 ), titanium diketone enolates (A2),titanium carboxylates (A3), titanyl carboxylates (A4), and titanylcarboxylate salts (A5 ); and a toner binder for developing electrostaticcharge images, which binder comprises a polycondensate polyester resin,

[0007] said polyester resin being a product formed in the presence of atleast one tin-containing catalyst (B) selected from the group consistingof dioctyltin oxide (B1), monobutyltin oxide (B2), and dibutyltin oxide(B3), with the content of tributyltin compounds in (B3) being not morethan 250 ppm.

DETAILED DISCLOSURE OF THE INVENTION

[0008] In the following, the present invention is described in detail.

[0009] According to the invention, a polycondensate polyester resinformed in the presence of the above-mentioned titanium-containingcatalyst (A) and/or the above-mentioned tin-containing catalyst (B) isused. It is also possible to use two or more species of (A) and/or twoor more species of (B) combinedly.

[0010] Other polymerization catalysts than (A) or (B), for example zincacetate, tetrabutoxytitanate, and dibutyltin oxide with a content oftributyltin compounds exceeding 250 ppm, cannot produce such effectsthat can be produced in accordance with the invention.

[0011] Among (A), the titanium halide (A1) is not particularlyrestricted but includes, among others, dichlorotitanium,trichlorotitanium, tetrachorotitanium, trifluorotitanium,tetrafluorotitanium, and tetrabromotitanium.

[0012] The titanium diketone enolate (A2) is not particularly restrictedbut includes, among others, titanium acetylacetonate, titaniumdiisopropoxide bisacetylacetonate, and titanyl acetylacetonate. Amongthose species of (A2), titanium acetylacetonate is preferred.

[0013] The titanium carboxylate (A3) is not particularly restricted butmay be, for example, a titanium salt of an aliphatic carboxylic acidcontaining 1 to 32 carbon atoms (A3-1), or a titanium salt of anaromatic carboxylic acid containing 7 to 38 carbon atoms (A3-2). In thecase of titanium salts of dibasic or further polybasic carboxylic acids,one or two or more carboxyl groups may coordinates with each titaniumatom, and there may occur a free carboxyl group or groups notcoordinating with titanium.

[0014] (A3-1) is not particularly restricted but may be, for example, analiphatic monocarboxylic acid titanium salt (A3-1a), an aliphaticdicarboxylic acid titanium salt (A3-1b), an aliphatic tricarboxylic acidtitanium salt (A3-1c), or an aliphatic tetra- to octa- or further basicpolybasic carboxylic acid titanium salt (A3-1d).

[0015] (A3-1a) is not particularly restricted but includes, amongothers, titanium formate, titanium acetate, titanium propionate, andtitanium octanoate. (A3-1b) is not particularly restricted but includes,among others, titanium oxalate, titanium succinate, titanium maleate,titanium adipate, and titanium sebacate. (A3-1c) is not particularlyrestricted but includes, among others, titanium hexanetricarboxylate andtitanium isooctanetricarboxylate. (A3-1d) is not particularly restrictedbut includes, among others, titanium octanetetracarboxylate and titaniumdecanetetracarboxylate.

[0016] (A3-2) is not particularly restricted but may be, for example, anaromatic monocarboxylic acid titanium salt (A3-2a), an aromaticdicarboxylic acid titanium salt (A3-2b), an aromatic tricarboxylic acidtitanium salt (A3-2c), or an aromatic tetra- to octa- or further basicpolybasic carboxylic acid titanium salt (A3-2d).

[0017] (A3-2a) is not particularly restricted but includes, amongothers, titanium benzoate and the like. (A3-2b) is not particularlyrestricted but includes, among others, titanium phthalate, titaniumterephthalate, titanium isophthalate, titanium1,3-naphthalenedicarboxylate, titanium 4,4-biphenyldicarboxylate,titanium 2,5-toluenedicarboxylate, and titanium anthracenedicarboxylate.(A3-2c) is not particularly restricted but includes, among others,titanium trimellitate and titanium 2,4,6-naphthalenetricarboxylate.(A3-2d) is not particularly restricted but includes, among others,titanium pyromellitate and titanium 2,3,4,6-naphthalenetetracarboxylate.

[0018] Among these titanium carboxylates (A3), (A3-2) are preferred, and(A3-2b) are more preferred.

[0019] The titanyl carboxylate (A4) is not particularly restricted butmay be, for example, a titanyl salt of an aliphatic carboxylic acidcontaining 1 to 32 carbon atoms (A4-1) or a titanyl salt of an aromaticcarboxylic acid containing 7 to 38 carbon atoms (A4-2). In the case oftitanyl salts of dibasic or further polybasic carboxylic acids, one ortwo or more carboxyl groups may coordinate with each titanium atom, andthere may occur a free carboxyl group or groups not coordinating withtitanium.

[0020] (A4-1) is not particularly restricted but may be, for example, analiphatic monocarboxylic acid titanyl salt (A4-1a), an aliphaticdicarboxylic acid titanyl salt (A4-1b), an aliphatic tricarboxylic acidtitanyl salt (A4-1c), or an aliphatic tetra- to octa- or further basicpolybasic carboxylic acid titanyl salt (A4-1d).

[0021] (A4-1a) is not particularly restricted but includes, amongothers, titanyl formate, titanyl acetate, titanyl propionate, andtitanyl octanoate. (A4-1b) is not particularly restricted but includes,among others, titanyl oxalate, titanyl succinate, titanyl maleate,titanyl adipate, and titanyl sebacate. (A4-1c) is not particularlyrestricted but includes, among others, titanyl hexanetricarboxylate andtitanyl isooctanetricarboxylate. (A4-1d) is not particularly restrictedbut includes, among others, titanyl octanetetracarboxylate and titanyldecanetetracarboxylate.

[0022] (A4-2) is not particularly restricted but may be, for example, anaromatic monocarboxylic acid titanyl salt (A4-2a), an aromaticdicarboxylic acid titanyl salt (A4-2b), an aromatic tricarboxylic acidtitanyl salt (A4-2c), or an aromatic tetra- to octa- or further basicpolybasic carboxylic acid titanyl salt (A4-2d).

[0023] (A4-2a) is not particularly restricted but includes, amongothers, titanyl benzoate and the like. (A4-2b) is not particularlyrestricted but includes, among others, titanyl phthalate, titanylterephthalate, titanyl isophthalate, titanyl1,3-naphthalenedicarboxylate, titanyl 4,4-biphenyldicarboxylate, titanyl2,5-toluenedicarboxylate, and titanyl anthracenedicarboxylate. (A4-2c)is not particularly restricted but includes, among others, titanyltrimellitate and titanyl 2,4,6-naphthalenetricarboxylate. (A4-2d) is notparticularly restricted but includes, among others, titanylpyromellitate and titanyl 2,3,4,6-naphthalenetetracarboxylate.

[0024] The titanyl carboxylate salt (A5 ) is not particularly restrictedbut includes, among others, alkali metal (e.g. lithium, sodium,potassium) salts and alkaline earth metal (e.g. magnesium, calcium,barium) salts of those titanyl carboxylates mentioned above as (A4-1b),(A4-1c), (A4-1d), (A4-2b), (A4-2c) or (A4-2d) [(A5-1b), (A5-1c),(A5-1d), (A5-2b), (A5-2c), and (A5-2d), respectively]. Among these,titanyl maleate salts and titanyl oxalate salts are preferred.

[0025] The amount of (A) that is to be used is not particularlyrestricted but the lower limit is preferably set at 0.01%, morepreferably at 0.02%, still more preferably at 0.03%, most preferably at0.05%, and the upper limit preferably at 5%, more preferably at 2%,still more preferably at 1.5%, most preferably at 0.8%, based on thetotal weight of the polyol and polycarboxylic acid used for obtainingthe polyester resin. At addition levels not lower than 0.01%, thepolycondensation catalyst activity is manifested to a satisfactoryextent and, at levels not higher than 5%, the catalyst activityincreases with the increase in catalyst amount. When a catalyst additionlevel is used within the above range to obtain a polyester resin for atoner binder, various characteristics required of the resulting tonerscomprising the toner binder become better and, in particular, thequality of images on the photoconductor under low-temperature andlow-humidity conditions becomes better.

[0026] In the above and subsequent descriptions, “%” means “% byweight”, unless otherwise specified.

[0027] Among the tin-containing catalysts (B), the dibutyltin oxide (B3)having a tributyltin compound (hereinafter referred to as “TBT” forshort) content of not higher than 250-ppm can be obtained bysynthesizing dibutyltin oxide in the conventional manner, for example,by carrying out the Grignard reaction using butyl chloride, as astarting material, after tin tetrachloride to give dibutyltin oxide,then dispersing the obtained dibutyltin oxide in an organic solvent andremoving TBT as a solvent-soluble fraction by filtration(dispersion-washing method), or by removing TBT by extraction with anorganic solvent using a Soxhlet extractor, for instance(recycling-washing method). Commercially available dibutyltin oxideproducts generally contain 400 to 600 ppm of TBT, hence are not suitedfor use in the practice of the invention.

[0028] In the foregoing and subsequent descriptions, “ppm” means “ppm onthe weight basis”.

[0029] The TBT referred to above is not particularly restricted butincludes, as typical homologues, bis(tributyltin) oxide (tributyltinoxide), tributyltin chloride, and tributyltin acetate.

[0030] The organic solvent to be used for dispersion-washing is notparticularly restricted but includes, among others, alcohols (methanol,ethanol, isopropyl alcohol, etc.), ketones (acetone,diethyl ketone,methyl ethyl ketone, etc.), ethers (diethyl ether, tetrahydrofuran,etc.), other polar solvents (dimethyl sulfoxide, dimethylformamide,etc.), aliphatic hydrocarbons (hexane, pentane, etc.), aromatichydrocarbons (toluene, xylene, etc.), and combinations of such organicsolvents.

[0031] Among those, the combination of an alcohol and an aliphatichydrocarbon and the combination of an alcohol and an aromatichydrocarbon are preferred, and the combination of methanol and hexaneand the combination of methanol and toluene are more preferred.

[0032] The amount of the organic solvent that is to be used in the stepof dispersion-washing is not particularly restricted but generally issuch that the organic solvent amounts to 0.1 to 500 parts, preferably 1to 200 parts, more preferably 5 to 100 parts, per part of dibutyltinoxide. In the above and subsequent descriptions, “part(s)” means“part(s) by weight”.

[0033] The method of dispersing is not particularly restricted but, forexample, the method comprising stirring using a stirring blade, shakingin a vessel, or using a ball mill for wet dispersion may be employed.After dispersion, the solvent can be removed by filtration,centrifugation, or some other appropriate method.

[0034] The organic solvent to be used in recycling-washing is notparticularly restricted but includes, among others, those alcohols,ketones, ethers, aliphatic hydrocarbons, and aromatic hydrocarbonsmentioned above, and combinations of these organic solvents.

[0035] The TBT content of (B3) is generally 250 ppm or lower.Preferably, the upper limit is 150 ppm, more preferably 75 ppm, stillmore preferably 25 ppm, most preferably 1 ppm. The lower limit ispreferably not more than 0.5 ppm. When the TBT content exceeds 250 ppm,the quality of images on the photoconductor deteriorates underlow-temperature and low-humidity conditions.

[0036] The amount of (B) that is to be used is not particularlyrestricted but the lower limit is preferably set at 0.01%, morepreferably at 0.02%, still more preferably at 0.03%, most preferably at0.05%, and the upper limit preferably at 5%, more preferably at 2%,still more preferably at 1.5%, most preferably at 0.8%, based on thetotal weight of the polyol and polycarboxylic acid used for obtainingthe polyester resin. At addition levels not lower than 0.01%, thepolycondensation catalyst activity is manifested to a satisfactoryextent and, at levels not higher than 5%, the catalyst activityincreases with the increase in catalyst amount. When a toner bindercomprising the polyester resin obtained by employing a catalyst amountlevel within the above range is used, various characteristics requiredof the resulting toners comprising the toner binder become better and,in particular, the quality of images on the photocondenser underlow-temperature and low-humidity conditions becomes better. In caseswhere (A) and (B) are used in combination, the catalyst amount ispreferably within the above range, too.

[0037] When (B2) and/or (B3) is used as (B), the amount thereof to beused is not particularly restricted but preferably is such that the TBTcontent in the polyester resin obtained amounts to not more than 0.6ppm, more preferably not more than 0.3 ppm, still more preferably notmore than 0.1 ppm, most preferably not more than 0.05 ppm, in order thatthe quality of images on the photoconductor under low-temperature andlow-humidity conditions may be more improved.

[0038] Preferred among these catalysts (A) and (B) are titanium diketoneenolates (A2), titanium carboxylates (A3), titanyl carboxylate salts(A5), and combinations of these. More preferred are (A2), aromaticcarboxylic acid titanium salts (A3-2), titanyl aliphatic carboxylatesalts (A5-1), titanyl aromatic carboxylate salts (A5-2), andcombinations of these. Still more preferred are titaniumacetylacetonate, (A3-2b), alkali metal salts among (A5-1b), alkali metalsalts among (A5-2b), and combinations of these. Still more preferred aretitanium terephthalate, titanium isophthalate, titanium orthophthalate,titanyl oxalate salts, titanyl maleate salts, and combinations of these.Most preferred are titanium terephthalate, titanyl oxalate potassiumsalt, and the combination of these.

[0039] The polycondensate polyester resin to constitute the toner binderof the present invention is not particularly restricted but includes,among others, polyester resins (X), which are polyol-polycarboxylic acidpolycondensates, modified polyester resins (Y) obtained by furtherreacting (X) with a polyepoxide (C), and the like. The resins (X), (Y)and so on may be used singly or as a mixture of two or more species.

[0040] The polyol is not particularly restricted but includes, amongothers, diols (G) and tri- or further hydric polyhydric polyols (H). Thepolycarboxylic acid is not particularly restricted but includes, amongothers, dicarboxylic acids (I) and tri- or further basic polybasicpolycarboxylic acids (J).

[0041] The polyester resin constituting the toner binder of theinvention is not particularly restricted but specifically includes, forexample, those listed below. These may also be used in combination.

[0042] (X1): Linear polyester resins produced by using (G) and (I).

[0043] (X2): Nonlinear polyester resins produced by using (H) and/or

[0044] (J) together with (G) and (I).

[0045] (Y1): Modified polyester resins produced by reacting (X2) with(C).

[0046] The diol (G) is not particularly restricted but includes, amongothers, diols having an hydroxyl value of 180 to 1,900 mg KOH/g, morespecifically alkylene glycols containing 2 to 12 carbon atoms (ethyleneglycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol,1,6-hexanediol, etc.); alkylene ether glycols (diethylene glycol,triethylene glycol, dipropylene glycol, polyethylene glycol,polypropylene glycol, polybutylene glycol, etc.); alicyclic diols(1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols(bisphenol A, bisphenol F, bisphenol S, etc.); adducts of theabove-mentioned alicyclic diols with an alkylene oxide(s) containing 2to 4 carbon atoms [ethylene oxide (hereinafter referred to as “EO” forshort), propylene oxide (hereinafter referred to as “PO” for short),butylene oxide (hereinafter referred to as “BO” for short), etc.]; andadducts of the above-mentioned bisphenols with an alkylene oxide(s) (EO,PO, BO, etc.).

[0047] Preferred among these are alkylene glycols containing 2 to 12carbon atoms, alkylene oxide adducts of bisphenols, and combinationsthereof. More preferred are alkylene oxide adducts of bisphenols, andthe combinations thereof with an alkylene glycol(s) containing 2 to 12carbon atoms.

[0048] The hydroxyl value and acid value referred to in the above andsubsequent descriptions are determined by the methods defined in JIS K0070.

[0049] The tri- or further hydric polyhydric polyol (H) is notparticularly restricted but includes, among others, polyols having ahydroxyl value of 150 to 1,900 mg KOH/g, more specifically tri- toocta-hydric or further-hydric polyhydric aliphatic alcohols (glycerol,triethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.);adducts of the above-mentioned aliphatic polyols with an alkyleneoxide(s) containing 2 to 4 carbon atoms (EO, PO, BO, etc.); trisphenols(trisphenol PA etc.); novolak resins (phenol novolak, cresol novolak,etc.); adducts of the above-mentioned trisphenols with an alkylene oxidecontaining 2 to 4 carbon atoms (EO, PO, BO, etc.); and adducts of theabove-mentioned novolak resins with an alkylene oxide(s) containing 2 to4 carbon atoms (EO, PO, BO, etc.).

[0050] Preferred among them are tri- to octa-hydric and further-hydricpolyhydric aliphatic alcohols and alkylene oxide adducts of novolakresin. Most preferred are alkylene oxide adducts of novolak resin.

[0051] The dicarboxylic acid (I) is not particularly restricted butincludes, among others, dicarboxylic acids having an acid value of 180to 1,250 mg KOH/g, more specifically alkylenedicarboxylic acidscontaining 4 to 36 carbon atoms (succinic acid, adipic acid, sebacicacid, dodecenylsuccinic acid, etc.); alkenylenedicarboxylic acidscontaining 4 to 36 carbon atoms (maleic acid, fumaric acid, etc.);aromatic dicarboxylic acids containing 8 to 36 carbon atoms (phthalicacid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid,etc.); and the like. Preferred among them are alkenylenedicarboxylicacids containing 4 to 20 carbon atoms and aromatic dicarboxylic acidscontaining 8 to carbon atoms. The combined use of two or more of thesewill not produce any problem. Also usable as (I) are acid anhydrides andlower (C₁₋₄) alkyl esters (methyl ester, ethyl ester, isopropyl ester,etc.) of those mentioned above.

[0052] The tri- or further basic polybasic polycarboxylic acid (J) isnot particularly restricted but includes, among others, polycarboxylicacids having an acid value of 150 to 1,250 mg KOH/g, more specificallyaromatic polycarboxylic acids containing 9 to 20 carbon atoms(trimellitic acid, pyromellitic acid, etc.); vinyl polymers ofunsaturated carboxylic acids (styrene-maleic acid copolymer,styrene-acrylic acid copolymer, α-olefin-maleic acid copolymers,styrene-fumaric acid copolymer, etc.); and the like. Preferred amongthese are aromatic polycarboxylic acids containing 9 to 20 carbon atoms.Most preferred are trimellitic acid and pyromellitic acid. Also usableas the tri- or further-basic polybasic polycarboxylic acids (J) are acidanhydrides and lower (C₁₋₄) alkylesters (methyl ester, ethylester,isopropylester, etc.) of those mentioned above.

[0053] It is also possible to copolymerize a hydroxycarboxylic acid (K)together with (G), (H), (I) and (J).

[0054] The hydroxycarboxylic acid (K) is not particularly restricted butincludes, among others, hydroxystearic acid and hydrogenated castor oilfatty acids.

[0055] The polyepoxide (C) is not particularly restricted but includes,among others, polyglycidyl ethers [ethylene glycol diglycidyl ether,tetramethylene glycol diglycidyl ether, bisphenol A diglycidyl ether,bisphenol F diglycidyl ether, glycerol triglycidyl ether,pentaerythritol tetraglycidyl ether, glycidyl etherified phenol novolak(average degree of polymerization 3 to 60), etc.]; and diene oxides(pentadiene dioxide, hexadiene dioxide, etc.). Preferred among them arepolyglycidyl ethers. More preferred are ethylene glycol diglycidyl etherand bisphenol A diglycidyl ether.

[0056] The number of epoxy groups per molecule of (C) is preferably 2 to8, more preferably 2 to 6, most preferably 2 to 4.

[0057] The epoxy equivalent of (C) is not particularly restricted butpreferably is 50 to 500. The lower limit is more preferably 70, mostpreferably 80, and the upper limit is more preferably 300, mostpreferably 200. When the number of epoxy groups or/and the epoxyequivalent are within the respective ranges mentioned above, both thedevelopability and fixability become better. It is more desirable thatboth the number of epoxy groups per molecule and the epoxy equivalent bewithin the respective ranges mentioned above.

[0058] The polyol-to-polycarboxylic acid ratio, as expressed in terms ofhydroxyl group [OH]-to-carboxyl group [COOH] equivalent ratio[OH]/[COOH], is preferably 2/1 to 1/2, more preferably 1.5/1 to 1/1.3,most preferably 1.3/1 to 1/1.2. The polyol and polycarboxylic acidspecies to be used are preferably selected in view of molecular weightadjustment so that the polyester-based toner binder finally prepared mayhave a glass transition point of 40 to 90° C.

[0059] Specific examples of (X1) include, but are not limited to, thefollowing (1) to (3), among others.

[0060] (1) Polycondensate of bisphenol A-PO (2 moles)adduct/terephthalic acid.

[0061] (2) Polycondensate of bisphenol A-EO (4 moles) adduct/bisphenolA-PO (2 moles) adduct/terephthalic acid.

[0062] (3) Polycondensate of bisphenol A-PO (2 moles) adduct/bisphenolA-PO (3 moles) adduct/terephthalic acid/isophthalic acid/maleicanhydride.

[0063] Specific examples of (X2) include, but are not limited to, thefollowing (4) to (10), among others.

[0064] (4) Polycondensate of bisphenol A-EO (2 moles) adduct/bisphenolA-PO (3 moles) adduct/terephthalic acid/phthalic anhydride/trimelliticanhydride.

[0065] (5) Polycondensate of bisphenol A-PO (2 moles) adduct/bisphenolA-PO (3 moles) adduct/bisphenol A-EO (2 moles) adduct/phenol novolak-PO(5 moles) adduct/terephthalic acid/maleic anhydride/dimethylterephthalate/trimellitic anhydride.

[0066] (6) Polycondensate of Bisphenol A-EO (2 moles) adduct/bisphenolA-PO (2 moles) adduct/terephthalic acid/trimellitic anhydride.

[0067] (7) Polycondensate of bisphenol A-EO (2 moles) adduct/bisphenolA-PO (2 moles) adduct/terephthalic acid/maleic anhydride/trimelliticanhydride.

[0068] (8) Polycondensate of bisphenol A-PO (2 moles) adduct/bisphenolA-PO (3 moles) adduct/terephthalic acid/isophthalic acid/maleicanhydride/trimellitic anhydride.

[0069] (9) polycondensate of bisphenol A-PO (2 moles) adduct/bisphenolA-PO (3 moles) adduct/phenol novolak-EO adduct/isophthalicacid/trimellitic anhydride.

[0070] (10) Polycondensate of bisphenol A-EO (2 moles) adduct/bisphenolA-PO (2 moles) adduct/phenol novolak-PO (5 moles) adduct/terephthalicacid/fumaric acid/trimellitic anhydride.

[0071] Specific examples of (Y1) include, but are not limited to, thefollowing (11) to (20), among others.

[0072] (11) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-EO (2 moles) adduct/phenol novolak-PO(5 moles) adduct/terephthalic acid/dodecenylsuccinic anhydride byreaction with tetramethylene glycol diglycidyl ether.

[0073] (12) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-PO (3 moles) adduct/bisphenol A-EO (2moles) adduct/phenol novolak-PO (5 moles) adduct/terephthalicacid/dodecenylsuccinic anhydride by reaction with ethylene glycoldiglycidyl ether.

[0074] (13) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-PO (3 moles) adduct/phenol novolak-EOadduct/isophthalic acid/maleic anhydride/trimellitic anhydride byreaction with bisphenol A diglycidyl ether.

[0075] (14) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-PO (3 moles) adduct/bisphenol A-EO (2moles) adduct/phenol novolak-EO adduct/terephthalic acid/isophthalicacid/trimellitic anhydride by reaction with bisphenol A diglycidylether.

[0076] (15) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-PO (3 moles) adduct/bisphenol A-EO (2moles) adduct/phenol novolak-PO (5 moles) adduct/terephthalicacid/isophthalic acid/maleic anhydride/trimellitic anhydride by reactionwith bisphenol A diglycidyl ether.

[0077] (16) Modified polyester derived from polycondensate of bisphenolA-PO (3 moles) adduct/phenol novolak-PO (5 moles) adduct/terephthalicacid/fumaric acid/trimellitic anhydride by reaction with ethylene glycoldiglycidyl ether.

[0078] (17) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/phenol novolak-PO (5 moles) adduct/terephthalicacid/dodecenylsuccinic anhydride/trimellitic anhydride by reaction withtetramethylene glycol diglycidyl ether.

[0079] (18) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-EO (2 moles) adduct/phenol novolak-EOadduct/terephthalic acid/trimellitic anhydride by reaction with ethyleneglycol diglycidyl ether.

[0080] (19) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-PO (3 moles) adduct/phenol novolak-PO(5 moles) adduct/terephthalic acid/trimellitic anhydride by reactionwith bisphenol A diglycidyl ether.

[0081] (20) Modified polyester derived from polycondensate of bisphenolA-PO (2 moles) adduct/bisphenol A-EO (2 moles) adduct/terephthalicacid/trimellitic anhydride by reaction with glycidyl etherified phenolnovolak.

[0082] Toner binders are required to have different physical propertiesaccording to their intended use, for full-color use or monochrome use.Accordingly, the polyester resins are designed in different ways.

[0083] Thus, highly glossy images are required for full-color use, henceit is necessary to reduce the binder viscosity whereas, for monochromeuse, gloss is not particularly required but hot offset is regarded asimportant, hence highly elastic binders are needed.

[0084] For obtaining highly glossy images of value in full-color copiersor the like, (X1), (X2), (Y1), and mixtures of these are preferred. Inthis case, low viscosity is preferred and, therefore, the proportion of(H) and/or (J) constituting the polyester resins is preferably such thatthe sum of moles of (H) and (J) amounts to 0 to 20 mole percent, morepreferably 0 to 15 mole percent, most preferably 0 to 10 mole percent,relative to the sum of moles of (G) to (J).

[0085] For attaining high hot offset resistance of use in monochromecopiers and so forth, (X2), (Y1), and mixtures of these are preferred.In this case, high elasticity is preferred and, therefore, polyesterresins produced by using both (H) and (J) are particularly preferred.The proportion of (H) plus (J) is preferably such that the sum of thenumbers of moles of (H) and (J) is 0.1 to 40 mole percent, morepreferably 0.5 to 25 mole percent, most preferably 1 to 20 mole percent,relative to the sum of the numbers of moles of (G) to (J).

[0086] In the case of polyester resins for full-color use, thetemperature (TE) at which the complex viscosity amounts to 100 Pa·s ispreferably 90 to 170° C., more preferably 100 to 165° C., mostpreferably 105 to 150° C. At 170° C. or below, satisfactory gloss isobtained and, at 90° C. or above, good heat resistance /storagestability are attained.

[0087] TE can be determined, for example, by subjecting a block preparedafter 30 minutes of melting and kneading of the resin at 130° C. and 70rpm using a laboratory plastomill to complex viscosity (η*) measurementsusing a commercial dynamic viscoelasticity measuring apparatus whilevarying the resin temperature.

[0088] From the gloss viewpoint, the THF-insoluble matter content of thepolyester resin for full-color use is preferably not more than 10%,still more preferably not more than 5%.

[0089] The THF-insoluble fraction and THF-soluble fraction can bedetermined by the following method.

[0090] About 0.5 g of the sample is accurately weighed in a 200-mlground stoppered Erlenmeyer flask, 50 ml of THF is added and, after 3hours of refluxing with stirring and the subsequent cooling, theinsoluble matter is filtered off using a glass filter. The THF-insolublematter content (%) is calculated from the weight ratio between theweight of the resin fraction on the glass filter after 3 hours of dryingunder vacuum at 80° C. and the sample weight.

[0091] This filtrate is used as the THF-soluble fraction in themolecular weight measurement to be described later herein.

[0092] In the case of polyester resins for monochrome use, thetemperature (TG) at which the storage elastic modulus (G′) of thepolyester resin amounts to 6,000 Pa is preferably 130 to 230° C., morepreferably 140 to 230° C., most preferably 150 to 230° C., from the hotoffset resistance viewpoint.

[0093] TG can be determined, for example, by subjecting a block preparedafter 30 minutes of melting and kneading of the resin at 130° C. and 70rpm using a laboratory plastomill to storage modulus (G′) measurementsusing a commercial dynamic viscoelasticity measuring apparatus whilevarying the resin temperature.

[0094] From the low temperature fixability and heat resistance/storagestability viewpoint, the temperature (TE) at which the complex viscosity(η*) of a polyester resin for monochrome use amounts to 1,000 Pa-s ispreferably 80 to 140° C., more preferably 90 to 135° C., most preferably105 to 130° C.

[0095] The polyester resin for monochrome use preferably has atetrahydrofuran (THF)-insoluble matter content of 5 to 70%, morepreferably 10 to 60%, most preferably 15 to 50%. At THF-insoluble mattercontent levels not lower than 5%, good hot offset resistance is obtainedand, at levels not exceeding 70%, good low temperature fixability isattained.

[0096] For both monochrome and full-color uses, the polyester resinpreferably has a peak top molecular weight of 1,000 to 30,000, morepreferably 1,500 to 25,000, most preferably 1,800 to 20,000. When thepeak top molecular weight is 1,000 or more, the heat resistance/storagestability and powder flowability become improved and, when it is notmore than 30,000, the grindability of the toner becomes improved and theproductivity becomes better.

[0097] In the above and the subsequent description, the peak topmolecular weight and number average molecular weight of a polyesterresin are determined for the THF-soluble fraction by GPC under thefollowing conditions.

[0098] Apparatus: Tosoh HLC-8120

[0099] Columns: TSK gel GMHXL (two columns) TSK gel Multipore HXL-M (onecolumn)

[0100] Measurement temperature: 40° C.

[0101] Sample solution: 0.25% solution in THF

[0102] Solution injection size: 100 μl

[0103] Detector: Refractive index detector

[0104] Reference material: Polystyrene

[0105] The molecular weight corresponding to the maximum peak height onthe chromatogram obtained is referred to as “peak top molecular weight”.

[0106] For both monochrome and full-color uses, the Tg of the polyesterresin is preferably within the range of 40 to 90° C., more preferably 50to 80° C., most preferably 55 to 75° C. When the Tg is within the rangeof 40° C. to 90° C., the heat resistance/storage stability and lowtemperature fixability become better.

[0107] The Tg of a polyester resin, so referred to hereinabove andhereinafter, is determined by the method (DSC method) prescribed in ASTMD3418-82 using Seiko Denshi Kogyo's DSC 20, SSC/580.

[0108] The method of producing the linear polyester resin (X1) is notparticularly restricted but may be, for example, the method comprisingheating the diol (G), dicarboxylic acid (I) and polycondensationcatalyst at 180° C. to 260° C. for effecting dehydrocondensation underatmospheric pressure and/or reduced pressure conditions to give thepolyester resin (X1).

[0109] The method of producing the nonlinear polyester resin (X2) is notparticularly restricted but may be, for example, the one comprisingheating the diol (G), dicarboxylic acid (I), at least trihydric polyol(H) and polycondensation catalyst at 180° C. to 260° C. for effectingdehydrocondensation under atmospheric pressure and/or reduced pressureconditions and further subjecting the tri- or further basic polybasicpolycarboxylic acid (J) to reaction to give the polyester resin (X2). Itis also possible to subject the tri- or further basic polybasicpolycarboxylic acid (J) to reaction simultaneously with the diol (G),dicarboxylic acid (I) and tri- or further basic polyhydric polyol (H).

[0110] The method of producing the modified polyester resin (Y1) is notparticularly restricted but may be, for example, the one comprisingadding the polyepoxide (C) to the nonlinear polyester resin (X2) andcarrying out a molecule extension reaction of the polyester at 180° C.to 260° C. to give the modified polyester resin (Y1).

[0111] The toner binder according to the invention may also comprise twoor more polyester resin species.

[0112] The toner binder according to the invention may contain, wherenecessary, at least one mold release agent (D) selected from the groupconsisting of carnauba wax (D1), Fischer-Tropsch wax (D2), paraffin wax(D3) and polyolefin wax (D4).

[0113] (D1) is not particularly restricted but includes, among others,natural carnauba wax, fatty acid-free carnauba wax, etc.

[0114] (D2) is not particularly restricted but includes, among others,petroleum-derived Fischer-Tropsch waxes (e.g. Schumann Sasol's ParaflintH1, Paraflint H1N4, Paraflint C105), natural gas-derived Fischer-Tropschwaxes (e.g. Shell MDS's FT 100 etc.), and purification products derivedfrom these Fischer-Tropsch waxes by, for example, fractionalcrystallization (e.g. Nippon Seiro's MDP-7000, MDP-7010).

[0115] (D3) is not particularly restricted but includes, among others,petroleum wax-based paraffin waxes (Nippon Seiro's paraffin waxes HNP-5,HNP-9, HNP-11).

[0116] (D4) is not particularly restricted but includes, among others,polyethylene waxes (e.g. Sanyo Chemical Industries' Sanwax 171P, SanwaxLEL 400 P), and polypropylene waxes (Sanyo Chemical Industries' Viscol550P, Viscol 660P).

[0117] Among them, carnauba waxes and Fischer-Tropsch waxes arepreferred. More preferred are carnauba waxes and Petroleum-derivedFischer-Tropsch waxes. The use of such a wax as a mold release agentresults in more improved low temperature fixability when the binder isused in preparing toners.

[0118] When the toner binder of the invention contains such mold releaseagent (D), the content of (D) is preferably 0.01 to 20%, more preferably0.1 to 15%, most preferably 0.5 to 10%, based on the total weight of thepolyester resin plus (D). When an addition level of the mold releaseagent is within the range of 0.01 to 20%, the resulting toners acquiremore improved hot offset resistance.

[0119] The toner binder of the present invention may contain, wherenecessary, a charge control agent (E).

[0120] (E) is not particularly restricted but includes, among others,nigrosine dyes, quaternary ammonium salt compounds, quaternary ammoniumsalt group-containing polymers, metal-containing azo dyes, salicylicacid metal salts, sulfonic acid group-containing polymers,fluorine-containing polymers, and halo-substituted aromaticring-containing polymers.

[0121] When the toner binder of the invention contains such chargecontrol agent (E), the content of (E) is not particularly restricted butpreferably is 0.01 to 5%, more preferably 0.02 to 4%, based on the totalweight of the polyester resin plus (E).

[0122] The polyester resin of the invention may contain another resin orthe like, where necessary.

[0123] The other resin is not particularly restricted but includes,among others, styrenic resins [e.g. styrene-alkyl (meth) acrylatecopolymers, styrene-diene monomer copolymers], epoxy resins (e.g.bisphenol A-epichlorohydrin addition condensates), and urethane resins(e.g. diol-diisocyanate polyaddition products).

[0124] Generally, the other resin has a weight average molecular weightof 1,000 to 2,000,000.

[0125] The content of the other resin in the toner binder is notparticularly restricted but preferably is 0 to 40%, more preferably 0 to30%, most preferably 0 to 20%, based on the total weight of thepolyester resin plus mold release agent.

[0126] When two or more polyester resins according to the invention areused in combination, or when one polyester resin is admixed with a moldrelease agent and/or another resin, powder mixing or melt mixing may becarried out in advance or mixing may be carried out in tonerpreparation.

[0127] The temperature in carrying out melt mixing is not particularlyrestricted but generally is 80 to 180° C., preferably 100 to 170° C.,more preferably 120 to 160° C.

[0128] It is unfavorable to mix at excessively low temperatures sincesatisfactory mixing cannot be accomplished but the system may beinhomogeneous. When the mixing temperature in mixing two or morepolyester resins together is excessively high, averaging due totransesterification and other reactions may occur, and it becomesimpossible to maintain those resin properties which are required oftoner binders.

[0129] The mixing time for melt mixing is not particularly restrictedbut preferably is 10 seconds to 30 minutes, more preferably 20 secondsto 10 minutes, most preferably 30 seconds to 5 minutes. When the mixingtime in mixing two or more polyester resins together is excessivelylong, averaging due to transesterification and other reactions mayoccur, making it impossible to maintain those resin properties which arerequired of toner binders.

[0130] The mixing apparatus for melt mixing is not particularlyrestricted but includes, among others, batch type mixing apparatus, suchas reaction vessels, and continuous mixing apparatus. For attaininguniform mixing at an adequate temperature for a short period of time, acontinuous mixing apparatus is preferred. The continuous mixingapparatus is not particularly restricted but includes, among others,extruders, continuous kneaders, and three-roll mills. Among them,extruders and continuous kneaders are preferred.

[0131] In the case of powder mixing, mixing can be attained usingconventional mixing conditions and a conventional mixing apparatus.

[0132] The mixing conditions in powder mixing are not particularlyrestricted but the mixing temperature is preferably 0 to 80° C., morepreferably 10 to 60° C. The mixing time is not particularly restrictedbut preferably is not shorter than 3 minutes, more preferably 5 to 60minutes. The mixing apparatus is not particularly restricted butincludes, among others, Henschel mixers, Nauta mixers, and Banburymixers. Henschel mixers are preferred, however.

[0133] An example of the production of an electrophotographic tonerusing the toner binder of the present invention is now described. Thetoner is constituted of the toner binder of the invention and acolorant, if necessary together with one or more of various additivessuch as mold release agents, charge control agents, and flowabilityproviding agents.

[0134] The content of the toner binder in the toner is not particularlyrestricted but, when a dye or pigment is used as the colorant, it ispreferably 70 to 98%, more preferably 74 to 96%. When a magnetic powderis used, it is preferably 20 to 85%, more preferably 35 to 65%.

[0135] The colorant is not particularly restricted but includes, amongothers, dyes, pigments, and magnetic powders. Specifically, there may bementioned carbon black, Sudan Black SM, Fast Yellow G, Benzidine Yellow,Pigment Yellow, Indofast Orange, IRGAZINRed, baranitaniline red,Toluidine Red, carmine, Pig FB ment Orange R, Lake Red 2G, Rhodamine FB,Rhodamine B Lake, Methyl Violet B Lake, phthalocyanine blue, PigmentBlue, Prilliant Green, phthalocyanine green, Oil Yellow GG, Kayaset YG,Orasol Brown B, Oil Pink OP, magnetite, and iron black.

[0136] The content of the colorant in the toner is not particularlyrestricted but, when a dye or pigment is used, for instance, it ispreferably 2 to 15%. When a magnetic powder is used, it is preferably 15to 70%, more preferably 30 to 60%.

[0137] The mold release agent (D) is not particularly restricted butmention may be made of those mentioned hereinabove. In using (D), it maybe the same as or different from the mold release agent mentioned above.

[0138] The amount of the mold release agent in the toner is notparticularly restricted but is preferably 0 to 10%, more preferably 1 to7%.

[0139] The charge control agent (E) is not particularly restricted butincludes, among others, those mentioned hereinabove.

[0140] The content of (E) in the toner is not particularly restrictedbut preferably is 0 to 5%, more preferably 0.01 to 4%.

[0141] The flowability providing agent is not particularly restrictedbut includes, among others, colloidal silica, alumina powders, titaniumoxide powders, and calcium carbonate powders.

[0142] The content of the flowability-providing agent in the toner ispreferably 0 to 5%.

[0143] The method of producing toners is not particularly restricted butmay comprise, for example, kneading and grinding method. After dryblending of the toner constituents mentioned above, the mixture ismelt-kneaded and then finely ground using a jet mill or the like,followed by air classification, whereby particles generally having aparticle diameter D50 of 2 to 20 um are obtained.

[0144] The particle diameter D50 can be determined using a Coultercounter [e.g. trademark: Multisizer III (product of Coulter)].

[0145] The toner prepared by using the toner binder of the invention, ifnecessary after admixing with carrier particles such as a magneticpowder (e.g. iron powder, nickel powder, ferrite, magnetite), glassbeads, and/or ferrite whose surface is coated with a resin (e.g. acrylicresin, silicone resin), is used as an electric latent image developer.It is also possible to form electric latent images by friction with sucha member as a charged blade in lieu of the use of carrier particles.

[0146] The toner is then fixed to a support (e.g. paper, polyester film)by the conventional heated roll fixation method, for instance, to give arecorded product.

BEST MODES FOR CARRYING OUT THE INVENTION

[0147] The following examples further illustrate the present invention.They are, however, by no means limitative of the scope of the presentinvention. In the following, “part(s)” means “part(s) by weight”.

[0148] The methods of determining the softening point and TBT content asused in the examples and comparative examples are as follows.

[0149] 1. Softening Point Determination Method

[0150] A flow tester is used, and the temperature is raised at aconstant rate under the following conditions. The temperature at whichthe discharge amount becomes ½ is the softening point.

[0151] Apparatus: Shimadzu Flow Tester CFT-500D

[0152] Load: 20 kgf/cm²

[0153] Die: 1 mm Φ−1 mm

[0154] Rate of temperature rise: 6° C./min

[0155] Sample amount: 1.0 g

[0156] 2. TBT Content Determination Method

[0157] (1) Apparatus: GC-MS (JEOL's JMS GC mate II)

[0158] (2) GC conditions

[0159] Column: CP-SIL-5CB (film thickness 0.25 micrometer, insidediameter 0.25 mm, length 60 m)

[0160] Measurement temperature: 100° C. to 210° C. (5° C./min), 210° C.to 300° C. (10° C./min)

[0161] (3) MS conditions

[0162] Detection: SIM (selective ion monitoring)

[0163] Acceleration voltage: 2.5 kV

[0164] Ion source temperature: 230° C.

[0165] Measured mass number: 277

[0166] (4) Procedure

[0167] The sample (2.5 g) is dissolved in chloroform. The solution isadded to a hydrochloric acid-acetonitrile solution, and the mixture isheated for chlorination. The supernatant is concentrated, and theconcentrate is extracted with hexane. After dehydration, the extract isconcentrated. Propylation is effected using a propylmagnesium bromidesolution, followed by treatment with diluted sulfuric acid andextraction with hexane. The extract is concentrated to 1 mL. Thisconcentrate is used as the sample.

Production Example 1

[0168] [Dibutyltin oxide Purification-1]

[0169] Dibutyltin oxide (L) (5.0 parts) with a TBT content of 453 ppmwas weighed in an Erlenmeyer flask, 50 parts of methanol and 50 parts ofhexane were added, the contents were stirred by means of a magneticstirrer at room temperature for 1 hour, and the solvent was thenfiltered off. This procedure was repeated ten times to give 3.5 parts ofdibutyltin oxide (M) having a TBT content of 5.12 ppm.

[0170] Dibutyltin oxide (N) (3.2 parts) having a TBT content of 0.92 ppmwas obtained in the same manner except that the purification procedurewas repeated 20 times.

[0171] [Dibutyltin oxide Purification-2]

[0172] Dibutyltin oxide (P) (5.0 parts) with a TBT content of 505 ppmwas subjected to Soxhlet extraction with tetrahydrofuran for 10 hours togive 2.5 parts of dibutyltin oxide (Q) with a TBT content of 71.2 ppm.

[0173] <Evaluation in the Form of a Color Toner>

Example 1

[0174] [Linear Polyester Resin Synthesis]

[0175] A reaction vessel equipped with a condenser, stirrer and nitrogeninlet tube was charged with 430 parts of bisphenol A-PO (2 moles)adduct, 300 parts of bisphenol A-PO (3 moles) adduct, 257 parts ofterephthalic acid, 65 parts of isophthalic acid, 10 parts of maleicanhydride, and 2 parts of potassium titanyl oxalate as apolycondensation catalyst, and the reaction was carried out under anitrogen stream at 220° C. for 10 hours while distilling off thebyproduct water. Then, the reaction was further allowed to proceed underreduced pressure (5 to 20 mm Hg). When the acid value reached 5, theproduct was taken out, cooled to room temperature, and ground to give alinear polyester resin (X1-1).

[0176] (X1-1) contained no THF-insoluble fraction and had an acid valueof 8, a hydroxyl value of 12, a Tg of 59° C., a number average molecularweight of 6,890, and a peak top molecular weight of 19,800.

[0177] [Nonlinear Polyester Resin Synthesis]

[0178] A reaction vessel equipped with a condenser, stirrer and nitrogeninlet tube was charged with 350 parts of bisphenol A-EO (2 moles)adduct, 326 parts of bisphenol A-PO (3 moles) adduct, 278 parts ofterephthalic acid, 40 parts of phthalic anhydride, and 1.5 parts ofpotassium titanyl oxalate as a polycondensation catalyst, and thereaction was carried out under a nitrogen stream at 230° C. for 10 hourswhile distilling off the byproduct water. Then, the reaction was furtherallowed to proceed under reduced pressure (5 to 20 mm Hg). When the acidvalue reached 2, the flask contents were cooled to 180° C., 62 parts oftrimellitic anhydride was added, and the reaction was allowed to proceedat ordinary pressure for 2 hours in a tightly closed condition, theproduct was then taken out, cooled to room temperature, and ground togive a nonlinear polyester resin (X2-1).

[0179] (X2-1) contained no THF-insoluble fraction and had an acid valueof 36, a hydroxyl value of 17, a Tg of 69° C., a number averagemolecular weight of 3,810, and a peak top molecular weight of 11,400.

[0180] [Toner Binder Synthesis]

[0181] 400 parts of (X1-1) and 600 parts of (X2-1) were melted and mixedtogether in a continuous kneader at a jacket temperature of 150° C. Theresidence time was 3 minutes. The melted resin was cooled to 30° C. in 4minutes using a steel belt cooler, followed by grinding to give a tonerbinder (TB1) of the invention.

EXAMPLE 2

[0182] [Linear Polyester Resin Synthesis]

[0183] A linear polyester resin (X1-2) was produced by carrying out thereaction in the same manner as in the case of (X1-1) in Example 1 exceptthat 2 parts of titanium terephthalate was used as the polycondensationcatalyst, followed by cooling to room temperature and grinding.

[0184] (X1-2) contained no THF-insoluble fraction and had an acid valueof 7, a hydroxyl value of 11, a Tg of 59° C., a number average molecularweight of 7,010, and a peak top molecular weight of 20,100.

[0185] [Nonlinear Polyester Resin Synthesis]

[0186] A nonlinear polyester resin (X2-2) was produced by carrying outthe reaction in the same manner as in the case of (X2-1) in Example 1except that 1.5 parts of titanium terephthalate was used as thepolycondensation catalyst, followed by cooling to room temperature andgrinding.

[0187] (X2-2) contained no THF-insoluble fraction and had an acid valueof 33, a hydroxyl value of 15, a Tg of 69° C., a number averagemolecular weight of 4,130, and a peak top molecular weight of 11,830.

[0188] [Toner Binder Synthesis]

[0189] The polyester (X1-2) (500 parts) and the polyester (X2-2) (500parts) were subjected to powder mixing in a Henschel mixer for 5 minutesto give a toner binder resin (TB2) of the invention.

EXAMPLE 3

[0190] [Linear Polyester Resin Synthesis]

[0191] A linear polyester resin (X1-3) was produced by carrying out thereaction in the same manner as in the case of (X1-1) in Example 1 exceptthat 2 parts of dibutyltin oxide (M) was used as the polycondensationcatalyst. After 10-hour reaction at 220° C., the acid value was 15.(X1-3) had a TBT content of less than 0.01 ppm (below the detectionlimit of GC-MS-SIM), a THF-insoluble matter content of 0%, an acid valueof 7, a hydroxyl value of 12, a Tg of 59° C., a number average molecularweight of 6,700, and a peak top molecular weight of 18,500.

[0192] [Nonlinear Polyester Resin Synthesis]

[0193] A nonlinear polyester resin (X2-3) was produced by carrying outthe reaction in the same manner as in the case of (X2-1) in Example 1except that 2 parts of dibutyltin oxide (M) was used as thepolycondensation catalyst. After 3-hour reaction under reduced pressure(5 to 20 mm Hg), the acid value was 1.5.

[0194] (X2-3) had a TBT content of less than 0.01 ppm, a THF-insolublematter content of 0%, an acid value of 39, a hydroxyl value of 18, a Tgof 68° C., a number average molecular weight of 3,900, and a peak topmolecular weight of 12,400.

[0195] [Toner Binder Synthesis]

[0196] 400 parts of (X1-3) and 600 parts of (X2-3) were melted and mixedtogether in a continuous kneader at a jacket temperature of 150° C. Theresidence time was 3 minutes. The melted resin was cooled to 30° C. in 2minutes using a steel belt cooler, followed by grinding to give a tonerbinder (TB3) of the invention.

EXAMPLE 4

[0197] [Linear Polyester Resin Synthesis]

[0198] A linear polyester resin (X1-4) was produced by carrying out thereaction in the same manner as in the case of (X1-1) in Example 1 exceptthat 2 parts of dioctyltin oxide was used as the polycondensationcatalyst.

[0199] (X1-4) had a TBT content of less than 0.01 ppm, a THF-insolublematter content of 0%, an acid value of 7, a hydroxyl value of 11, a Tgof 58° C., a number average molecular weight of 7,050, and a peak topmolecular weight of 19,500.

[0200] [Nonlinear Polyester Resin Synthesis]

[0201] A nonlinear polyester resin (X2-4) was produced by carrying outthe reaction in the same manner as in the case of (X2-1) in Example 1except that 2 parts of monobutyltin oxide was used as thepolycondensation catalyst.

[0202] (X2-4) had a TBT content of less than 0.01 ppm, a THF-insolublematter content of 0%, an acid value of 36, a hydroxyl value of 18, a Tgof 69° C., a number average molecular weight of 3,830, and a peak topmolecular weight of 12,200.

[0203] [Toner Binder Synthesis]

[0204] 400 parts of (X1-4) and 600 parts of (X2-4) were melted and mixedtogether in a continuous kneader at a jacket temperature of 150° C. Theresidence time was 3 minutes. The melted resin was cooled to 30° C. in 4minutes using a steel belt cooler, followed by grinding to give a tonerbinder (TB4) of the invention.

Comparative Example 1-1

[0205] [Comparative Linear Polyester Resin Synthesis]

[0206] The reaction was carried out in the same manner as in the case of(X1-1) in Example 1 except that 2 parts of titanium tetrabutoxide wasused as the polycondensation catalyst. But a problem arose. Namely, thereaction stopped halfway due to catalyst deactivation and no morebyproduct water distilled off. Therefore, five 1.5-part portions oftitanium tetrabutoxide were added during the procedure. However, it wasimpossible to drive the reaction until an acid value of 5; no desiredpolycondensate was obtained. The reaction mixture assumed a strongviolet-brown color.

Comparative Example 1-2

[0207] [Comparative Linear Polyester Resin Synthesis]

[0208] The reaction was carried out in the same manner as in the case of(X1-1) in Example 1 except that 2 parts of titanium tetraglycoxide wasused as the polycondensation catalyst. The rate of reaction was slow, sothat the reaction was continued at atmospheric pressure for 16 hours andthen under reduced pressure for 8 hours to give a comparative linearpolyester resin (CX1-1).

[0209] (CX1-1) occurred as a violet-brown resin, contained noTHF-insoluble fraction, and had an acid value of 5, a hydroxyl value of11, a Tg of 58° C., a number average molecular weight of 6,500, and apeak top molecular weight of 20,200.

[0210] [Comparative Nonlinear Polyester Resin Synthesis]

[0211] The reaction was carried out in the same manner as in the case of(X2-1) in Example 1 except that 2 parts of titanium tetraglycoxide wasused as the polycondensation catalyst. But a problem arose. Namely, thereaction stopped halfway due to catalyst deactivation and no morebyproduct water distilled off. Therefore, four 1.5-part portions oftitanium tetraglycoxide were added during the procedure to give acomparative nonlinear polyester resin (CX2-1).

[0212] (CX2-1) occurred as a violet-brown resin, contained noTHF-insoluble fraction, and had an acid value of 33, a hydroxyl value of16, a Tg of 68° C., a number average molecular weight of 3,680, and apeak top molecular weight of 11,800.

[0213] [Comparative Toner Binder Synthesis]

[0214] 400 parts of (CX1-1) and 600 parts of (CX2-1) were melted andmixed together in a continuous kneader at a jacket temperature of 150°C. The residence time was 3 minutes. The melted resin was cooled to 30°C. in 4 minutes using a steel belt cooler, followed by grinding to givea comparative toner binder (CTB1). (CTB1) was a resin having a strongviolet-brown color.

Comparative Example 2

[0215] [Comparative Linear Polyester Resin Synthesis]

[0216] A comparative linear polyester resin (CX1-2) was producedfollowing the same reaction procedure as in the case of (X1-1) inExample 1 except that 0.2 parts of dibutyltin oxide (L) was used as thepolycondensation catalyst. After 10-hour reaction at 220° C., the acidvalue was 25.

[0217] (CX1-2) had a TBT content of 0.08 ppm, a THF-insoluble mattercontent of 0%, an acid value of 15, a hydroxyl value of 27, a Tg of 57°C., a number average molecular weight of 4,300, and a peak top molecularweight of 11,500.

[0218] [Comparative Nonlinear Polyester Resin Synthesis]

[0219] A comparative nonlinear polyester resin (CX2-2) was producedfollowing the same reaction procedure as in the case of (X2-1) inExample 1 except that 0.2 parts of dibutyltin oxide (P) was used as thepolycondensation catalyst. After 3-hour reaction under reduced pressure(5 to 20 mm Hg), the acid value was 25.

[0220] (CX2-2) had a TBT content of 0.09 ppm, a THF-insoluble mattercontent of 0%, an acid value of 45, a hydroxyl value of 27, a Tg of 63°C., a number average molecular weight of 3,500, and a peak top molecularweight of 8,200.

[0221] [Comparative Toner Binder Synthesis]

[0222] A comparative toner binder (CTB2) was produced in the same manneras in Example 3 except that (CX1-2) was used in lieu of (X1-3) and(CX2-2) in lieu of (X2-3).

Comparative Example 3

[0223] [Comparative Linear Polyester Resin Synthesis]

[0224] A comparative linear polyester resin (CX1-3) was producedfollowing the same reaction procedure as in the case of (X1-1) inExample 1 except that 2 parts of dibutyltin oxide (L) was used as thepolycondensation catalyst. After 10-hour reaction at 220° C., the acidvalue was 14.

[0225] (CX1-3) had a TBT content of 0.89 ppm, a THF-insoluble mattercontent of 0%, an acid value of 6, a hydroxyl value of 12, a Tg of 60°C., a number average molecular weight of 6,940, and a peak top molecularweight of 19,100.

[0226] [Comparative Nonlinear Polyester Resin Synthesis]

[0227] A comparative nonlinear polyester resin (CX2-3) was producedfollowing the same reaction procedure as in the case of (X2-1) inExample 1 except that 2 parts of dibutyltin oxide (P) was used as thepolycondensation catalyst. After 3-hour reaction under reduced pressure(5 to 20 mm Hg), the acid value was 1.6.

[0228] (CX2-3) had a TBT content of 0.97 ppm, a THF-insoluble mattercontent of 0%, an acid value of 40, a hydroxyl value of 19, a Tg of 68°C., a number average molecular weight of 3,760, and a peak top molecularweight of 11,950.

[0229] [Comparative Toner Binder Synthesis]

[0230] A comparative toner binder (CTB3) was produced in the same manneras in Example 3 except that (CX1-3) was used in lieu of (X1-3) and(CX2-3) in lieu of (X2-3).

Evaluation Examples 1 to 4 and Comparative Evaluation Examples 1 to 3

[0231] For each of the toner binders (TB1) to (TB4) of the invention andthe comparative toner binders (CTB1) to (CTB3), 100 parts of the tonerbinder was premixed with 5 parts of carnauba wax and 4 parts of a yellowpigment [toner yellow HG VP2155, product of Clariant] using a Henschelmixer [model FM10B, product of Mitsui Miike Kakoki], and the mixture waskneaded in a twin-screw kneader [model PCM-30, product of Ikegai Corp.].The mixture was then finely pulverized using a supersonic jet pulverizer[Labojet, product of Nippon Pneumatic Mfg. Co.], followed byclassification using an air classifier [model MDS-I, product of NipponPneumatic] to give toner particles with a particle diameter D50 of 8 μm.Then, 0.5 parts of colloidal silica [Aerosil R972, product of NipponAerosil] was admixed with 100 parts of the toner particles in a samplemill. In this way, toners (T1) to (T4) and comparative toners (CT1) to(CT3) were obtained.

[0232] The results of evaluations made by the following evaluationmethods are shown in Table 1.

[0233] [Evaluation Methods]

[0234] (1) Gloss Appearance Temperature (GLOSS)

[0235] A two-component developer for the evaluation was prepared byuniformly mixing up 30 parts of each toner and 800 parts of a ferritecarrier (F-150; product of Powdertech Co.). Unfixed images developed ona commercial copier (AR 5030; product of Sharp Corp.) using thedeveloper were fixed at a process speed of 120 mm/sec on a fixingmachine prepared by modifying the fixing unit of a commercial printer(LBP 2160; product of Canon Inc.) so that the heated roller temperaturemight be varied. The fixing roll temperature at which the fixed imageshowed a 60° gloss of not less than 10% was determined using acommercial glossmeter (MURAKAMI COLOR RESEARCH LABORATORY modelgmx-202-60) and recorded as the gloss appearance temperature.

[0236] (2) Hot Offset Occurrence Temperature (HOT)

[0237] Fixation was performed in the same manner as in theabove-mentioned GLOSS evaluation, and the occurrence or nonoccurrence ofhot offset onto fixed images was evaluated by the eye. The fixing rolltemperature at which hot offset occurred was recorded as the hot offsetoccurrence temperature.

[0238] (3) Color Tone

[0239] Image fixation was performed on OHP films at a fixing rolltemperature of 170° C. in the same manner as in the above-mentionedGLOSS evaluation, the fixed images were projected onto a screen using anoverhead projector, and the color tone was judged by the eye.

[0240] Evaluation criteria

[0241] “Good”: Vivid yellow.

[0242] “Fair”: Slightly blurred yellow.

[0243] “Poor”: Blurred.

[0244] (4) Toner Flowability

[0245] The toners were measured for static bulk densities using aHosokawa Micron's powder tester, and the flowability of each toner wasevaluated according to the following criteria. When the flowability is“fair” or better, the toner is suited for practical use.

[0246] Static Bulk Density

[0247] 36 g/100 ml or higher: toner flowability is “good”

[0248] 33-36: Better level than “fair” but worse than “good”

[0249] 30-33: “Fair”

[0250] 27-30: Better level than “poor” but worse than “fair”

[0251] less than 27: “Poor”

[0252] (5) Staining of the Photoconductor

[0253] Each developer prepared as described above under (1) wasconditioned in a low-temperature and low-humidity environment (10° C.,40% R.H.) for at least 8 hours. Using the developer and a commercialcopier (AR 5030; product of Sharp Corp.) in the same environment, 3,000copies were made, and the photoconductor was examined for staining andthe copied images were checked for quality.

[0254] Evaluation Criteria

[0255] “Excellent”: No photoconductor staining with the toner, and goodimage quality.

[0256] “Good”: A slight amount of the toner adhering to thephotoconductor but almost no deterioration (staining of whitebackground) in image quality.

[0257] “Fair”: A slight amount of the toner adhering to thephotoconductor and image quality deterioration (staining of whitebackground) observed.

[0258] “Poor”: A significant amount of the toner adhering to thephotoconductor, and marked image quality deterioration with whitestripes crossing images in addition to staining of white background.TABLE 1 GLOSS HOT Color Staining of the Toner (° C.) (° C.) toneFlowability photoconductor TBT content Evaluation Example 1 (T1)130 >200 Good Good Excellent — Evaluation Example 2 (T2) 130 >200 GoodGood Excellent — Evaluation Example 3 (T3) 130 >200 Good Good Good <0.01ppm Evaluation Example 4 (T4) 130 >200 Good Good Good <0.01 ppm Compar.Evaluation (CT1) 128 >200 Poor Poor Good — Example 1 Compar. Evaluation(CT2) 130   145 Fair Poor Poor   0.07 ppm Example 2 Compar. Evaluation(CT3) 135 >200 Good Good Poor   0.84 ppm Example 3

[0259] From Table 1, it is apparent that the toners prepared by usingthe toner binders of the invention ensure stable image quality evenunder low-temperature and low-humidity conditions and are superior incolor tone to the toners prepared from the conventional toner binders.Furthermore, it is evident that the polycondensation catalysts used inaccordance with the invention are superior in catalytic activity to theknown titanium-containing catalysts (titanium tetraglycoxide, titaniumtetrabutoxide).

[0260] <Evaluation in the Form of a Monochrome Toner-1>

EXAMPLE 5

[0261] [Modified Polyester Resin Synthesis]

[0262] A reaction vessel equipped with a condenser, stirrer and nitrogeninlet tube was charged with 549 parts of bisphenol A-PO (2 moles)adduct, 20 parts of bisphenol A-PO (3 moles) adduct, 133 parts ofbisphenol A-ethylene oxide (2 moles) adduct, 10 parts of phenol novolak(average degree of polymerization about 5)-EO (5 moles) adduct, 252parts of terephthalic acid, 19 parts of isophthalic acid, 10 parts oftrimellitic anhydride, and 2 parts of titanium acetylacetonate as apolycondensation catalyst, and the reaction was carried out under anitrogen stream at 230° C. for 10 hours while distilling off thebyproduct water. Then, the reaction was further allowed to proceed underreduced pressure (5 to 20 mm Hg) until the acid value reached not morethan 2. Then, 50 parts of trimellitic anhydride was added, the reactionwas allowed to proceed at ordinary pressure for 1 hour and then underreduced pressure (20 to 40 mm Hg) When the softening point arrived at105° C., 20 parts of bisphenol A diglycidyl ether was added. When asoftening point of 150° C. was attained, the product was taken out,cooled to room temperature, and ground to give a modified polyesterresin (Y1-1).

[0263] (Y1-1) had a softening point of 150° C., an acid value of 53, ahydroxyl value of 17, a Tg of 74° C., a number average molecular weightof 1,800, a peak top molecular weight of 6,700, and a THF-insolublematter content of 33%. This was used as a toner binder (TB5).

EXAMPLE 6

[0264] [Modified Polyester Resin Synthesis]

[0265] A modified polyester resin (Y1-2) was produced by carrying outthe reaction in the same manner as in the case of (Y1-1) in Example 5except that 2 parts of potassium titanyl maleate was used as thepolycondensation catalyst, followed by taking out at a softening pointof 150° C., cooling to room temperature and grinding.

[0266] (Y1-2) had a softening point of 150° C., an acid value of 51, ahydroxyl value of 16, a Tg of 74° C., a number average molecular weightof 1,940, a peak top molecular weight of 6,630, and a THF-insolublematter content of 35%. This was used as a toner binder (TB6).

EXAMPLE 7

[0267] [Nonlinear Polyester Resin Synthesis]

[0268] A reaction vessel equipped with a condenser, stirrer and nitrogeninlet tube was charged with 132 parts of bisphenol A-PO (2 moles)adduct, 371 parts of bisphenol A-PO (3 moles) adduct, 20 parts ofbisphenol A-EO (2 moles) adduct, 125 parts of phenol novolak (averagedegree of polymerization about 5)-PO (5 moles) adduct, 201 parts ofterephthalic acid, 25 parts of maleic anhydride, 35 parts of dimethylterephthalate, and 1.5 parts of potassium titanyl oxalate as apolycondensation catalyst, and the reaction was carried out under anitrogen stream at 230° C. for 10 hours while distilling off thebyproduct water. Then, the reaction was further allowed to proceed underreduced pressure (5 to 20 mm Hg). When the acid value became not morethan 2, the reaction mixture was cooled to 180° C. and 65 parts oftrimellitic anhydride was added. The reaction was allowed to proceed atordinary pressure in a tightly closed condition for 2 hours, and thereaction mixture was then taken out, cooled to room temperature, andground to give a nonlinear polyester resin (X2-5).

[0269] The nonlinear polyester resin (X2-5) had a softening point of142° C., an acid value of 30, a hydroxyl value of 17, a Tg of 57° C., anumber average molecular weight of 1,380, a peak top molecular weight of4,150, and a THF-insoluble matter content of 26%. This was used as atoner binder (TB7)

EXAMPLE 8

[0270] [Nonlinear Polyester Resin Synthesis]

[0271] A reaction vessel equipped with a condenser, stirrer and nitrogeninlet tube was charged with 410 parts of bisphenol A-PO (2 moles)adduct, 270 parts of bisphenol A-PO (3 moles) adduct, 110 parts ofterephthalic acid, 125 parts of isophthalic acid, 15 parts of maleicanhydride, and 2 parts of potassium titanyl oxalate as apolycondensation catalyst, and the reaction was carried out under anitrogen stream at 220° C. for 10 hours while distilling off thebyproduct water. Then, the reaction was further allowed to proceed underreduced pressure (5 to 20 mm Hg). When the acid value became not morethan 2, the reaction mixture was cooled to 180° C. and 25 parts oftrimellitic anhydride was added. The reaction was allowed to proceed atordinary pressure in a tightly closed condition for 2 hours and, then,the product was taken out, cooled to room temperature, and ground togive a nonlinear polyester resin (X2-6).

[0272] (X2-6) contained no THF-insoluble matter, and had an acid valueof 18, a hydroxyl value of 35, a Tg of 61° C., a number averagemolecular weight of 1,990, and a peak top molecular weight of 5,310.

[0273] [Modified Polyester Resin Synthesis]

[0274] A reaction vessel equipped with a condenser, stirrer and nitrogeninlet tube was charged with 317 parts of bisphenol A-EO (2 moles)adduct, 57 parts of bisphenol A-PO (2 moles) adduct, 298 parts ofbisphenol A-PO (3 moles) adduct, 75 parts of phenol novolak (averagedegree of polymerization about 5)-PO (5 moles) adduct, 30 parts ofisophthalic acid, 157 parts of terephthalic acid, 27 parts of maleicanhydride, and 1.5 parts of potassium titanyl oxalate as apolycondensation catalyst, and the reaction was carried out under anitrogen stream at 230° C. for 10 hours while distilling off thebyproduct water. Then, the reaction was further allowed to proceed underreduced pressure (5 to 20 mm Hg) and, when the acid value became notmore than 2, the reaction mixture was cooled to 180° C. Then, 68 partsof trimellitic anhydride was added, the reaction was allowed to proceedat ordinary pressure for 1 hour and then under reduced pressure (20 to40 mm Hg). When the softening point arrived at 120° C., 25 parts ofbisphenol A diglycidyl ether was added. When a softening point of 155°C. was attained, the product was taken out, cooled to room temperature,and ground to give a modified polyester resin (Y1-3).

[0275] (Y1-3) had a softening point of 155° C., an acid value of 10, ahydroxyl value of 29, a Tg of 58° C., a number average molecular weightof 3,120, a peak top molecular weight of 6,130, and a THF-insolublematter content of 36%.

[0276] [Toner Binder Synthesis]

[0277] 500 parts of (X2-6) and 500 parts of (Y1-3) were melted and mixedtogether in a continuous kneader at a jacket temperature of 150° C. Theresidence time was 3 minutes. The melted resin was cooled to 30° C. in 4minutes using a steel belt cooler, followed by grinding to give a tonerbinder (TB8) according to the invention.

EXAMPLE 9

[0278] [Nonlinear Polyester Resin Synthesis]

[0279] A nonlinear polyester resin (X2-7) was produced by carrying outthe reaction in the same manner as in the case of (X2-6) in Example 8except that 2 parts of titanium terephthalate was used as thepolycondensation catalyst, followed by cooling to room temperature andgrinding.

[0280] (X2-7) contained no THF-insoluble matter, and had an acid valueof 17, a hydroxyl value of 35, a Tg of 61° C., a number averagemolecular weight of 2,110, and a peak top molecular weight of 5,450.

[0281] [Modified Polyester Resin Synthesis]

[0282] A modified polyester resin (Y1-4) was produced by carrying outthe reaction in the same manner as in the case of (Y1-3) in Example 8except that 1.5 parts of titanium terephthalate was used as thepolycondensation catalyst, followed by cooling to room temperature andgrinding.

[0283] (Y1-4) had a softening point of 155° C., an acid value of 9, ahydroxyl value of 28, a Tg of 59° C., a number average molecular weightof 3,050, a peak top molecular weight of 6,010, and a THF-insolublematter content of 38%.

[0284] [Toner Binder Synthesis]

[0285] 500 parts of the polyester (X2-7) and 500 parts of the polyester(Y1-4) were subjected to powder mixing in a Henschel mixer for 5 minutesto give a toner binder resin (TB9) according to the invention.

EXAMPLE 10

[0286] [Modified Polyester Resin Synthesis]

[0287] The reaction was carried out in the same manner as in the case of(Y1-1) in Example 5 except that 2 parts of dibutyltin oxide (N) was usedas the polycondensation catalyst. The product was taken out at asoftening point of 145° C., cooled to room temperature, and ground togive a modified polyester resin (Y1-5).

[0288] (Y1-5) had a TBT content of less than 0.01 ppm, a softening pointof 151° C., an acid value of 54, a hydroxyl value of 17, a Tg of 73° C.,a number average molecular weight of 2,100, a peak top molecular weightof 6,500, and a THF-insoluble matter content of 34%. This was used as atoner binder (TB10)

EXAMPLE 11

[0289] [Nonlinear Polyester Resin Synthesis]

[0290] A nonlinear polyester resin (X2-8) was produced by carrying outthe reaction in the same manner as in the case of (X2-6) in Example 8except that 2 parts of dibutyltin oxide (N) was used as thepolycondensation catalyst, followed by cooling to room temperature andgrinding.

[0291] (X2-8) had a TBT content of less than 0.01 ppm, contained noTHF-insoluble matter, and had an acid value of 18, a hydroxyl value of33, a Tg of 62° C., a number average molecular weight of 2,100, and apeak top molecular weight of 5,400.

[0292] [Modified Polyester Resin Synthesis]

[0293] The reaction was carried out in the same manner as in the case of(Y1-3) in Example 8 except that 2 parts of dibutyltin oxide (O) was usedas the polycondensation catalyst. The product was taken out at asoftening point of 148° C., cooled to room temperature, and ground togive a modified polyester resin (Y1-6).

[0294] (Y1-6) had a TBT content of 0.13 ppm, a softening point of 153°C., an acid value of 9, a hydroxyl value of 31, a Tg of 58° C., a numberaverage molecular weight of 3,100, a peak top molecular weight of 6,100,and a THF-insoluble matter content of 33%.

[0295] [Toner Binder Synthesis]

[0296] 500 parts of (X2-8) and 500 parts of (Y1-6) were melted and mixedtogether in a continuous kneader at a jacket temperature of 150° C. Theresidence time was 3 minutes. The melted resin was cooled to 30° C. in 4minutes using a steel belt cooler, followed by grinding to give a tonerbinder (TB11) according to the invention.

Comparative Example 4

[0297] [Comparative Modified Polyester Resin Synthesis]

[0298] A comparative modified polyester resin (CY-1) was produced bycarrying out the reaction in the same manner as in the case of (Y1-1) inExample 5 except that 2 parts of dibutyltin oxide (P) was used as thepolycondensation catalyst.

[0299] (CY-1) had a TBT content of 0.91 ppm, a softening point of 150°C., an acid value of 54, a hydroxyl value of 16, a Tg of 74° C., anumber average molecular weight of 1,820, and a peak top molecularweight of 6,600, and a THF-insoluble matter content of 34%. This wasused as a toner binder (CTB4)

Evaluation Examples 5 to 11 and Comparative Evaluation Example 4

[0300] For each of the toner binders (TB5) to (TB11) according to theinvention and the comparative toner binder (CTB4), 100 parts of thetoner binder was premixed with 8 parts of carbon black MA-100 (productof Mitsubishi Chemical), 5 parts of carnauba wax and 1 part of thecharge control agent T-77 (product of Hodogaya Chemical) using aHenschel mixer [model FM10B, product of Mitsui Miike Kakoki], and themixture was kneaded in a twin-screw kneader [model PCM-30, product ofIkegai Corp.].

[0301] The mixture was then finely pulverized using a supersonic jetpulverizer [Labojet, product of Nippon Pneumatic Mfg. Co.], followed byclassification using an air classifier [model MDS-I, product of NipponPneumatic] to give toner particles with a particle diameter D50 of 9 μm.Then, 0.3 parts of colloidal silica [Aerosil R972, product of NipponAerosil] was admixed with 100 parts of the toner particles in a samplemill. In this way, toners (T5) to (T11) and a comparative toner (CT4)were obtained.

[0302] The results of evaluations made by the following evaluationmethods are shown in Table 2.

[0303] [Evaluation Methods]

[0304] (1) Minimal fixing temperature (MFT)

[0305] A two-component developer for the evaluation was prepared byuniformly mixing up 30 parts of each toner and 800 parts of a ferritecarrier (F-150; product of Powdertech Co.). Unfixed images developed ona commercial copier (AR 5030; product of Sharp Corp.) using thedeveloper were fixed at a process speed of 145 mm/sec on a fixingmachine prepared by modifying the fixing unit of a commercial copier (SF8400A; product of Sharp) so that the heated roller temperature might bevaried. The fixing roll temperature at which the residual image densityafter rubbing of the fixed image with a pad amounted to at least 70% wasrecorded as the minimal fixing temperature.

[0306] (2) Hot Offset Occurrence Temperature (HOT)

[0307] Fixation was performed in the same manner as in theabove-mentioned MFT evaluation, and the occurrence or nonoccurrence ofhot offset onto fixed images was evaluated by the eye. The fixing rolltemperature at which hot offset occurred was recorded as the hot offsetoccurrence temperature.

[0308] (3) Pigment Dispersibility

[0309] Each toner was measured for dielectric loss tangent (tanδ), andthis was employed as an indicator of pigment dispersibility.

[0310] Evaluation Criteria

[0311] “Good”: tanδ: not more than 10

[0312] “Fair”: tanδ: from 10 to 30

[0313] “Poor”: tanδ: not less than 30

[0314] Dielectric Loss Tangent Measurement Conditions

[0315] Apparatus: Ando Electric Company model TR-1100 dielectric lossmeasuring apparatus

[0316] Electrodes: Ando Electric Company model SE-43 powder electrodes

[0317] Measurement frequency: 1 kHz

[0318] (4) Staining of the Photoconductor

[0319] Each developer prepared as described above under (1) wasconditioned in a low-temperature and low-humidity environment (10° C.,40% R.H.) for at least 8 hours. Using the developer and a commercialcopier (AR 5030; product of Sharp Corp.) in the same environment, 3,000copies were made, and the photoconductor was examined for staining andthe copied images were checked for quality.

[0320] Evaluation Criteria

[0321] “Excellent”: No photoconductor staining with the toner, and goodimage quality.

[0322] “Good”: A slight amount of the toner adhering to thephotoconductor but almost no deterioration (staining of whitebackground) in image quality.

[0323] “Fair”: A slight amount of the toner adhering to thephotoconductor and image quality deterioration (staining of whitebackground) observed.

[0324] “Poor”: A significant amount of the toner adhering to thephotoconductor, and marked image quality deterioration with whitestripes crossing images in addition to staining of white background.TABLE 2 MFT HOT Pigment Staining of the TBT Toner (° C.) (° C.)dispersibility photoconductor content Evaluation Example 5 (T5) 140 225Good Good — Evaluation Example 6 (T6) 140 230 Good Good — EvaluationExample 7 (T7) 135 225 Good Excellent — Evaluation Example 8 (T8) 130230 Good Excellent — Evaluation Example 9 (T9) 130 230 Good Excellent —Evaluation Example 10 (T10) 135 225 Good Good <0.01 ppm   EvaluationExample 11 (T11) 135 225 Good Good 0.05 ppm Compar. Evaluation (CT4) 140225 Good Fair 0.82 ppm Example 4

[0325] From Table 2, it is seen that the toners prepared by using thetoner binders of the invention ensure stable image quality even underlow-temperature and low-humidity conditions and are comparable orsuperior in fixation characteristics and pigment dispersibility to thetoners prepared from the conventional toner binders.

[0326] <Evaluation in the Form of a Monochrome Toner-2>

EXAMPLE 12

[0327] [Modified Polyester Resin Synthesis]

[0328] A modified polyester resin (Y1-7) was produced following thereaction procedure for (Y1-1) in Example 5 except that 2 parts ofmonobutyltin oxide was used as the polycondensation catalyst. (Y1-7) hadan acid value of 54, a hydroxyl value of 17, a Tg of 74° C., a numberaverage molecular weight of 1,850, a peak top molecular weight of 6,750,a THF-insoluble matter content of 33%, and a TBT content of less than0.01 ppm. This was used as a toner binder (TB12).

EXAMPLE 13

[0329] [Nonlinear Polyester Resin Synthesis]

[0330] A nonlinear polyester resin (X2-9) was produced following thesame reaction procedure as for (X2-5) in Example 7 except that 2 partsof dioctyltin oxide was used as the polycondensation catalyst.

[0331] (X2-9) had a softening point of 145° C., an acid value of 28, ahydroxyl value of 16, a Tg of 58° C., a number average molecular weightof 1,480, a THF-insoluble matter content of 26%, and a TBT content ofless than 0.01 ppm. This was used as a toner binder (TB13).

EXAMPLE 14

[0332] [Nonlinear Polyester Resin Synthesis]

[0333] A nonlinear polyester resin (X2-10) was produced following thesame reaction procedure as for (X2-6) in Example 8 except that 2 partsof monobutyltin oxide was used as the polycondensation catalyst.

[0334] (X2-10) contained no THF-insoluble fraction, and had an acidvalue of 18, a hydroxyl value of 34, a Tg of 61° C., a number averagemolecular weight of 2,010, a peak molecular weight of 5,450, and a TBTcontent of less than 0.01%.

[0335] [Modified Polyester Resin Synthesis]

[0336] A modified polyester resin (Y1-8) was produced following the samereaction procedure as for (Y1-3) in Example 8 except that 2.5 parts ofdioctyltin oxide was used as the polycondensation catalyst.

[0337] (Y1-8) had an acid value of 11, a hydroxyl value of 29, a Tg of58° C., a number average molecular weight of 3,150, a peak top molecularweight of 6,050, a THF-insoluble matter content of 34%, and a TBTcontent of less than 0.01%.

[0338] [Toner Binder Synthesis]

[0339] 500 parts of (X2-10), 500 parts of (Y1-8) and 50 parts of aFischer-Tropsch wax (Paraflint H1) were melted and mixed together in acontinuous kneader at a jacket temperature of 150° C. the residence timewas 3 minutes. The melted resin was cooled to 30° C. in 4 minutes usinga steel belt cooler, followed by grinding to give a toner binder (TB14)according to the invention.

Comparative Example 5

[0340] [Comparative Nonlinear Polyester Resin Synthesis]

[0341] The same reaction procedure as for (X2-5) in Example 7 wascarried out except that 2 parts of titanium tetraglycoxide was used asthe polycondensation catalyst. Since the rate of reaction was slow, thereaction was carried out at atmospheric pressure for 16 hours and thenunder reduced pressure for 18 hours. The acid value was 6, however.After cooling to 180° C., 65 parts of trimellitic anhydride was added,and the reaction was further allowed to proceed at ordinary pressure ina tightly closed condition for 2 hours. Then the reaction mixture wastaken out, cooled to room temperature, and ground to give a comparativenonlinear polyester resin (CX2-4). (CX2-4) had a softening point of 131°C., an acid value of 33, a hydroxyl value of 22, a Tg of 51° C., anumber average molecular weight of 1,250, a peak top molecular weight of3,570, and a THF-insoluble matter content of 17%. This was used as acomparative toner binder (CTB5).

Evaluation Examples 12 and 13 and Comparative Evaluation Example 5

[0342] For each of the toner binders (TB12) and (TB13) according to theinvention and the comparative toner binder (CTB5), 100 parts of thetoner binder was premixed with 8 parts of carbon black MA-100 [productof Mitsubishi Chemical], 5 parts of a Fischer-Tropsch wax [Paraflint H1]and 1 part of the charge control agent T-77 [product of HodogayaChemical] using a Henschel mixer [model FM10B, product of Mitsui MiikeKakoki], and the mixture was kneaded in a twin-screw kneader [modelPCM-30, product of Ikegai Corp.]. The mixture was then finely pulverizedusing a supersonic jet pulverizer [Labojet, product of Nippon PneumaticMfg. Co.], followed by classification using an air classifier [modelMDS-I, product of Nippon Pneumatic] to give toner particles with aparticle diameter D50 of 9 μm. Then, 0.3 parts of colloidal silica[Aerosil R972, product of Nippon Aerosil] was admixed with 100 parts ofthe toner particles in a sample mill. In this way, toners (T12) and(T13) and a comparative toner (CT5) were obtained.

[0343] Evaluation Example 14

[0344] A toner (T14) was prepared using the toner binder (TB14)according to the invention in the same manner as in Evaluation Example12 except that the Fischer-Tropsch wax was not added.

[0345] The results of evaluations of (T12) to (T14) and (CT5) by theevaluation methods mentioned above are shown in Table 3. TABLE 3 MFT HOTPigment Staining of the TBT Toner (° C.) (° C.) dispersibilityphotoconductor content Evaluation Example 12 (T12) 140 ≧230    Good Good<0.01 ppm Evaluation Example 13 (T13) 135 225 Good Good <0.01 ppmEvaluation Example 14 (T14) 130 225 Good Good <0.01 ppm Compar.Evaluation (CT5) 135 150 Poor Fair — Example 5

[0346] From Table 3, it is seen that the toners prepared by using thetoner binders according to the invention ensure stable image qualityeven under low-temperature and low-humidity conditions and, further, areexcellent in hot offset resistance and pigment dispersibility.

INDUSTRIAL APPLICABILITY

[0347] The toner binders of the invention have the following effects.

[0348] 1. They ensure stable image quality even under low-temperatureand low-humidity conditions.

[0349] 2. They are excellent in both low temperature fixability and hotoffset resistance.

[0350] 3. They are less discolored and, when made into color toners,they ensure a good tone of color.

[0351] 4. They are excellent in flowability and pigment dispersibility,and in charging characteristics.

[0352] 5. They are produced by using a catalyst which does not containany tributyltin compound suspected of being an endocrine disrupter orcontains such compound only in a trace amount, hence they exert only aslight influence upon the environment.

1-9. (cancelled).
 10. A toner for developing electrostatic chargeimages, which comprises at least a toner binder and a colorant, saidtoner binder being a polycondensate polyester resin formed in thepresence of at least one titanium-containing catalyst (a) selected fromthe group consisting of a titanium halides (A1), a titanium diketoneenolate (A2), a titanium carboxylate (A3), a titanyl carboxylate (A4)and a titanyl carboxylate salt (A5).
 11. The toner for developingelectrostatic charge images according to claim 10, wherein the titaniumdiketone enolate (A2) is titanium acetylacetonate.
 12. The toner fordeveloping electrostatic charge images according to claim 10, whereinthe titanium carboxylate (A3) is an aromatic carboxylic acid titaniumsalt.
 13. The toner for developing electrostatic charge images accordingto claim 10, wherein the titanyl carboxylate salt (A5) is a titanylmaleate salt or a titanyl oxalate salt.
 14. A toner for developingelectrostatic charge images, which comprises at least a toner binder anda colorant, said toner binder being a polycondensate polyester resinformed in the presence of at least one tin-containing catalyst (B)selected from the group consisting of dioctyltin oxide (B1),monobutyltin oxide (B2), and dibutyltin oxide (B3), with the content oftributyltin compounds in (B3) being not more than 250 ppm.
 15. The tonerfor developing electrostatic charge images according to claim 14,wherein the tin-containing catalyst (B) is monobutyltin oxide (B2) ordibutyltin oxide (B3), and the content of tributyltin compounds in saidpolyester resin is not more than 0.6 ppm.
 16. The toner for developingelectrostatic charge images according to claim 10, wherein at least apart of the polyester resin being modified with a polyepoxide (C). 17.The toner for developing electrostatic charge images according to claim14, wherein at least a part of the polyester resin being modified with apolyepoxide (C).
 18. A toner binder for developing electrostatic chargeimages which binder comprises a polycondensate polyester resin, saidpolyester resin being a product formed in the presence of at least onetitanium-containing catalyst (A) selected from the group consisting of atitanium halides (A1) and a titanium carboxylate (A3).
 19. A tonerbinder for developing electrostatic charge images which binder comprisesa polycondensate polyester resin, said polyester resin being a productformed in the presence of at least one titanium-containing catalyst (A)selected from the group consisting of a titanium halides (A1), atitanium diketone enolate (A2), a titanium carboxylate (A3), a titanylcarboxylate (A4) and a titanyl carboxylate salt (A5), and which binderfurther comprises at least one mold release agent selected from thegroup consisting of carnauba waxes, Fischer-Tropsch waxes, paraffinwaxes and polyolefin waxes.
 20. A toner binder for developingelectrostatic charge images which binder comprises a polycondensatepolyester resin, said polyester resin being a product formed in thepresence of at least one titanium-containing catalyst (A) selected fromthe group consisting of a titanium halides (A1), a titanium diketoneenolate (A2), a titanium carboxylate (A3), a titanyl carboxylate (A4)and a titanyl carboxylate salt (A5), and which binder further comprisesa charge control agent.
 21. A toner binder for developing electrostaticcharge images, which binder comprises a polycondensate polyester resin,said polyester resin being a product formed in the presence of at leastone tin-containing catalyst (B) selected from the group consisting ofdioctyltin oxide (B1), monobutyltin oxide (B2), and dibutyltin oxide(B3), with the content of tributyltin compounds in (B3) being not morethan 250 ppm.
 22. The toner binder for developing electrostatic chargeimages according to claim 21, which further comprises at least one moldrelease agent selected from the group consisting of carnauba waxes,Fischer-Tropsch waxes, paraffin waxes and polyolefin waxes.
 23. Thetoner binder for developing electrostatic charge images according toclaim 21, which further comprises a charge control agent.